The required relative spacing between aircraft can be expressed in distance or in time. It is conventionally 90 seconds in the first case, and 3 nautical miles in the second. For some years now, the increase in air traffic, and the workload of the air traffic controllers evolving therefrom, has led to the consideration, in particular in the approach phase, of delegating responsibility for the management of the relative spacing between aircraft to the aircraft themselves and to their crews, whereas this responsibility at the moment is incumbent on air traffic control. Because of this, a number of technologies have been developed, enabling the aircraft to know the surrounding operational situation concerning them. These current technologies generally rely on the operation of equipment already installed in most aircraft: the collision avoidance system, known by the acronym TCAS which stands for “Traffic Collision Avoidance System”, coupled with an S mode transponder, also present on the current aircraft.
In practice, currently, the aircraft already transmit their position, their speed, their altitude, so that all the aircraft nearby can know their mutual positions and attitudes. Thus, devices aiming to couple the TCAS with the automatic pilot of an aircraft have been developed. However, they can be used only to control the speed of the following aircraft reactively. They cannot be used to control automatically the relative spacing between the aircraft. In practice, in these devices, the TCAS, in its capacity as standalone computer or computer integrated with other functional modules in an ISS, an acronym standing for “Integrated Surveillance System”, fulfils a primary function of surveillance of the surrounding traffic, a function commonly designated as “Safety Net”. The objective is then to transmit sound alerts and vertical movement setpoints when a conflict with another aircraft is detected.
For this, the TCAS systems, decoupled from the navigation systems, periodically compare the estimation of the movement of the aircraft relative to the surrounding aircraft.
Generally, the current aircraft, in the approach phase, follow the setpoints given by the air traffic controllers, following procedures of the “Remain Behind” type, consisting for the following aircraft in following a target aircraft at a given distance or with a given time spacing, or of the “Merge Behind” type, consisting for the following aircraft in reaching a point of convergence with a given distance or a given time spacing from the target aircraft.
In this context, studies are being conducted by official organizations with the aim of guaranteeing the safety of possible future ASAS manoeuvres managed on board the aircraft.
To this end, the invention proposes a method and a system making it possible to improve the safety and comfort of the flight during ASAS manoeuvres, the responsibility for which is delegated by air traffic control to the crew of an aircraft.
Recently, methods have been developed in order to favour having the management of the relative spacing between aircraft taken over by onboard systems implemented by the crew. For example, the patents FR2816091 and FR2894056 disclose methods aiming to study the trend of the relative spacing between a target aircraft (or master or leader) and the following aircraft (or slave). In both cases, the following aircraft analyses the data transmitted by the target aircraft, generally via a TCAS system, to communicate to its environment its position, it speed, its heading for example. The following aircraft, equipped with means for acquiring this information, deduces therefrom the trend of the relative spacing separating it from the target aircraft. However, these known methods are either purely reactive, such as the method described in FR2816091, which can cause “accordion” phenomena and does not make it possible to optimize the spacing between the target aircraft and the following aircraft, or they require knowledge of the flight plan and above all of the predictive trajectory of the target aircraft, as in the method described in FR2894056, which is not always possible and which, when said predictive trajectory of the target aircraft is available and transmitted to the environment of the target aircraft, requires potentially intensive acquisition processing operations.
The present invention makes it possible to overcome these drawbacks via the method described in Claim 1.